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bignick

Help! PTO belt twists & breaks!

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bignick
Has anyone experienced this problem? I've got an Allis-Chalmers 716H with 48" mower. The belt that drives the mower from the PTO twists itself and refuses to properly ride in the pulleys. Needless to say, I can mow for about 1/2 before the belt snaps in two! (I believe that it's a 71" belt .) I was wondering if the belt tensioning spring is getting tired, or maybe the rear or front idler is misaligned. The idlers seem to turn freely .. Any help is greatly appreciated! Thanks!

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Les
I have a 7119 Simplicity(repainted orange) that was driving me nuts as it was eating belts at the rate of one per hour. The problem with mine was the idler pulley on the tractor frame was loose. Three seconds with a 9/16" wrench and it has been on the same belt for two seasons.

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PatRarick
Make sure that you have the correct belt, that the belt is installed correctly, idler pulley bearings are good, you have the proper idler pulleys and that they are installed in the correct position, check the tightener idler pivot shaft and holes for wear, and do not mow with the deck in the raised position. Pat

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bignick
Les, PatRarick .. Thanks for replying! My problem may be this: I'm not certain why, but if I lower the mower deck, it scalps the lawn badly, even though I've got the mower's rollers adjusted for maximum height. As a result, I've been forced to mow with the deck in the raised position. Perhaps my "root-cause" is the mower deck having to be raised! I purchased the unit used.. is there a way to determine what is wrong with the mower deck so that I need to have it raised whilst mowing? Once again, thanks for your help!!

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UCD
Do you have the correct blades for your deck? Are the rollers worn? Are you using Simplicity belts How low in the deck are the blades? Has someone shimmed the blades to cut lower? Just some Questions that might effect cutting height. The correct belt for 716H MFG# 1690021 48" rotary mower P.T.O. Belt# 163011 Length 71.6" Type HA 1/2" X 11/32" Arbor drive Belt# 165048 Length 85.2" type HA 1/2" X 11/32" Aftermarket belts will work but will not last as they are not designed to be run twisted and on the back side of the belt. Simplicity belts are. Sipmpicty Belts cost more but they last, in the long run are cheaper. Anything free is worth what you pay for it This & $1.00 might get you a small Coffee Maynard aka/UCD

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CarlH
Another possiblity for scalping with a Simplicity deck is the adjustment of the front rocker arm assembly on the deck. One of my stalled projects is to modify this assembly for higher cutting heights. I'm stalled on lowering the top drive pulley after I've modified the rocker assy and rear roller mount brackets. Carl

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MikeES
As Carl stated, the deck needs to be adjusted on both ends. Is the deck tilted down in the front when lowered? The deck should be slightly higher in the front than the back when down. Maybe someone can link to the deck adjustment info. on this site. If the deck is not close to level, the drive pulley will be tilted and eat belts. Are you using the inside pulley on your cone clutch? The outside is for the tiller. Just a couple of ideas. Good Luck! Mike S.

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bignick
Thank you, everybody, for all the useful information! (I really appreciate it, what a knock-out discussion group!) I'll be looking at my tractor, hopefully again tonight .. Someone else motioned that some sort of pulley spacer is to be installed and removed that accommodates the snow-blower belt positioning? (I bought the snow-blower along with the tractor.) And, that non-removal of the spacer will also cause the PTO belt to twist & break .. But I've yet to look for that yet .. Also, is there a good place to post digital photos of the unit? That might indicate 1,000 words instantly! (Maybe the discussion group area is inappropriate for photos?) Thanks again everybody!

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Kent
You can upload pictures directly into your topic or reply. Or, you can put them in your user Gallery and use them over and over. Here's some instructions for using them: http://www.simpletractors.com/club2/faq_template.asp?Catid=5 Note that each picture must be 100kb or less, and your Gallery is limited to 500kb total. There's a link to picture compression tools in the Links section of the clubhouse... You can also put them in other places such as Shutterbug or Photoloft, then just link them in. The foot-draggin' Clubhouse Custodian...

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CarlH
Tom, On the AC 71x and Simplicity 7000 Series tractors, the PTO pivoting idler bracket has 2 pulleys in fixed positions. On the AC 900 and Simplicity 7100 Series tractors, the pivoting idler bracket has 1 pulley which has 2 mounting positions for proper belt alignment depending on whether a mower deck or front snowblower is being driven. The other idler pulley is mounted on a slotted bracket that allows some adjustment for belt length. Both series of tractors use spacers to mount the idler pulleys. The spacers are not added/removed when changing alignment on the 900/7100 series. On the 71x/7000 series, there is no way to change alignment since the snowblower is driven by an engine mounted front clutch. Another thing on twisted belts. I have noticed that belts that are too tight have more of a tendency to roll over or twist. Perhaps a previous owner installed a spring which applies too much tension.

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Roy_Wooten
Tom, I had a similar problem on my 6216 and it turned out to be a pressed steel pulley was closed in slightly and the belt was riding on the narrow corners instead of the tapered faces of the belt. this caused the belt to roll over an eventually snap after about 2 hours of use. It was a kevlar Simplicity $50 belt. After I located the problem and fixed it with a few nudges of my hammer a $23 carquest belt has been mowing 4 3/4 acres with no slippage or rollover for the last 5 months. ( In NC the grass grows from april to october.) Roy Wooten

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dlcentral
1 make sure the RIGHTbackside idler is used as per id #,, there are 2sounds like you need the smaller one///2 make sure there is at least 1/2 in clear between belt as it goes forward//3 check bushings for excess wear at the swivel frt. hitch assy.Proper belt length is 71.5in. #163011

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goatfarmer
My 3410 LandLord had a similar problem a few years ago. It would flip the belt after a few minutes of mowing. Then it was back to the dealer for a new one,'cause the old one was ruined.What I did to fix it was replace the bearings in the center arbor on the deck. They were bad,and must have been putting strain on everything.Hasn't happened since. kenny L

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bignick
Thanks again, everyone, for all your replies! I'm checking for all the issues everyone had emailed to me. But I've found something else that might be causing my belt twisting. As I examined my idler pulleys, I've notice that the idler pulley, (the one positioned directly below the PTO drive pulley), is not in direct alignment. It appears that the idler pulley is rotated on its vertical axis, so that the two are not situated in the same plane. Perhaps this is 'normal' or maybe the idler bracket got twisted during a belt-break. I'm including a photograph.. I hope you can see what I'm talking about! I'm hoping that someone can tell me if this is normal or not .. (The photo was taken from the left rear of the tractor.) I've also posted a photo of my 716H on my "Area" on this discussion group. Thanks again!! [url="pop_download.asp?mode=Edit&dir=bignick&file=390"][/url]

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Dutch
Nick, Let me address your three issues separately. 1) Snowthrower on a 718H is driven off the front PTO (separate clutch on front of engine), therefore the snowthrower has nothing to do with the center PTO used for the mower deck. 2) It's almost impossible for a 718H mower deck to scalp, unless something is wrong. Remove the deck from the tractor. Remove both covers and arbor belt. Closely inspect for loose or noisy bearings in blade arbors. Check that deck sheet metal isn't bent or rotted. Spin each blade by hand and make sure they spin freely and without noise. Make sure the idler pulley swings freely and is not binding. Make sure the idle pulley spins freely and the spring applies tension. Check for wear between the rollers and the roller shaft. When you crank the adjusters, the roller shaft should move. Many times the mechanism is rusted. If yours is, free it up. 3) From your photo, the backside idler pulley looks okay (it's supposed to be "bent"). Make sure to use a GENUINE Simplicity belt. Make sure the belt is under any belt guards (if used). Adjust deck and route belt as per appropriate illustration in this manual > http://www.simplicitytechpubs.com/6767PRINT/PDF_files/TP_100_2978_02_AT_S.pdf

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